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Thursday, May 31, 2012

Counting penguins by satellite

Satellite imagery isn’t just for evading traffic jams and admiring your house from space. Peter Fretwell and his colleagues from the British Antarctic Survey, University in Minnesota, Scripps Institute of Oceanography and the Australian Antarctic Division used satellites to count Emperor penguins.

Emperor penguins (Aptenodytes fosteri) breed each year on the Antarctic sea ice. Until now, only five out of dozens of colonies have been regularly monitored. Therefore, conservationists have been able to make only rudimentary estimates as to the total number of birds. The best guess was that there were 135,000 to 175,000 breeding pairs. Fretwell and his associates felt they could do much better with satellites.

Emperor penguins offer the aspiring wildlife imager a number of advantages. For one thing, they’re large animals, reaching well over a meter in height. More importantly, they live in a barren monochromatic landscape where anything that’s not white is likely to be a penguin, a penguin’s shadow, or a penguin’s guano. With a bit of fiddling, researchers were able to distinguish between those three things well enough to get a fairly accurate bird count.

So, how many Emperor penguins were there? In 2009, the year of the study, the researchers estimated that there were close to 300,000 breeding pairs, at least twice as many as previously thought and very good news for the penguins. Unfortunately, with the diminishing of the sea ice due to climate change, the penguins probably won’t be able to enjoy those large numbers for long.

You can see Fretwell discuss the results below: